Powering Guages and Senders

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Powering Guages and Senders

As a step towards my turbo install I've added a guage pod. There was room under the stereo so I velcroed the autometer senders for the EGT and fuel pressure guages there. For the lights in the guages I took power from the ashtray light circuit (which wasn't being used). So now the lights on the guage turn on when the rest of the console lights do.

The senders themselves were powered from the radio circuit and this is a problem. As I'm sure everyone is aware your radio turns off when you crank the engine over. My guages go crazy when this happens. The boost guage is mechanical so it's fine but the others vibrate and jump wildly from having their power cut off abruptly.

Is there somewhere else I should tap this power so they get power only when the key is on? I'd like them to be powered in all positions but "off". The guages and senders draw about 150ma. Is there a way I could plug a capacitor in with some diodes so the guage pod stores about 2 seconds of juice while you're cranking the engine over? Any electronics wizards care to speculate on what size cap I'd need?

I don't want to power the radio (on the same circuit) at the same time so my 10 year old foggy electronics tells me to add a diode to stop the current from flowing through to the radio. This seem to be correct?

Use 1N4001 or 1N4002 diodes. If you can find them, Schottky diodes rated for at least 1A and 50V will be even better, such as a 1N5817. You may need to dig under the steering wheel to find the IGN and ACC wires.

For the backlighting, tie one wire (e.g. WHITE) to the +12V wire at one of the panel lights (such as the hazard flasher button or other backlighting wire. Then find the other wire that is controlled by the dimming circuit, and tie the other wire (e.g. BLACK) to that. This will allow your gauges to dim along with your instrument panel.